U.S. patent application number 15/344778 was filed with the patent office on 2018-05-10 for system and method for starting gas turbine engines.
The applicant listed for this patent is General Electric Company. Invention is credited to Koji Asari, Michael Allen Clawson, Mikhel Hawkins, Mauro Hayama, Thomas Charles Swager, Ming Tian, Xin Zhao.
Application Number | 20180128182 15/344778 |
Document ID | / |
Family ID | 60268456 |
Filed Date | 2018-05-10 |
United States Patent
Application |
20180128182 |
Kind Code |
A1 |
Hayama; Mauro ; et
al. |
May 10, 2018 |
SYSTEM AND METHOD FOR STARTING GAS TURBINE ENGINES
Abstract
A method of starting a gas turbine engine includes determining
an abnormal shutdown condition during operation of the gas turbine
engine and determining a first set of lightoff parameters for the
gas turbine engine. The method also includes restarting the gas
turbine engine using the first set of lightoff parameters. The
method further includes iteratively determining subsequent first
sets of lightoff parameters and restarting the gas turbine engine
using a respective subsequent first set of the determined
subsequent first sets of lightoff parameters until the gas turbine
maintains a first set of operational parameters, where the first
set of operational parameters is representative of a robust
lightoff of the gas turbine engine.
Inventors: |
Hayama; Mauro; (Mason,
OH) ; Zhao; Xin; (West Chester, OH) ; Tian;
Ming; (Mason, OH) ; Hawkins; Mikhel;
(Cincinnati, OH) ; Asari; Koji; (Sharonville,
OH) ; Swager; Thomas Charles; (Maineville, OH)
; Clawson; Michael Allen; (Cincinnati, OH) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
General Electric Company |
Schenectady |
NY |
US |
|
|
Family ID: |
60268456 |
Appl. No.: |
15/344778 |
Filed: |
November 7, 2016 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
F05D 2270/092 20130101;
F05D 2220/323 20130101; F05D 2220/32 20130101; F05D 2270/304
20130101; F05D 2260/85 20130101; F02C 7/262 20130101 |
International
Class: |
F02C 7/262 20060101
F02C007/262 |
Claims
1. A method of starting a gas turbine engine, said method
comprising: determining an abnormal shutdown condition during
operation of the gas turbine engine; determining a first set of
lightoff parameters for the gas turbine engine; restarting the gas
turbine engine using the first set of lightoff parameters; and
iteratively, determining subsequent first sets of lightoff
parameters and restarting the gas turbine engine using a respective
subsequent first set of the determined subsequent first sets of
lightoff parameters until the gas turbine engine maintains a first
set of operational parameters, the first set of operational
parameters representative of a robust lightoff of the gas turbine
engine.
2. The method in accordance with claim 1 further comprising:
determining a partial lightoff of the gas turbine engine;
iteratively, determining a second set of lightoff parameters; and
restarting the gas turbine engine using the second set of lightoff
parameters until the gas turbine engine maintains the first set of
operational parameters.
3. The method in accordance with claim 1 further comprising:
determining a no lightoff condition of the gas turbine engine;
iteratively, determining a third set of lightoff parameters; and
restarting the gas turbine engine using the third set of lightoff
parameters until the gas turbine engine maintains the first set of
operational parameters.
4. The method in accordance with claim 1, wherein restarting the
gas turbine engine using the first set of lightoff parameters
comprises determining a rotational velocity of a rotor of the gas
turbine engine and increasing the rotational velocity if a first
condition is met, the first condition including the rotational
velocity being at least one of: substantially equal to a windmill
speed value; and less than a first predetermined rotational
velocity value.
5. The method in accordance with claim 4, wherein determining the
first set of lightoff parameters comprises determining a flow rate
of fuel into a combustor of the gas turbine engine and an
operational status of an ignitor coupled to the combustor, and
wherein restarting the gas turbine engine using the first set of
lightoff parameters further comprises injecting, at a first flow
rate, fuel into the combustor, and energizing the ignitor, if a
second condition is met, the second condition including the
rotational velocity being greater than a second predetermined
rotational velocity value.
6. The method in accordance with claim 5 further comprising
determining a temperature of a flow of exhaust gas exiting the gas
turbine engine, wherein the first set of operational parameters
includes at least one of the exhaust gas temperature being greater
than a predetermined temperature value, a temperature rate of
change value being greater than a predetermined temperature rate of
change value, and a rate of change of the rotational velocity being
greater than a predetermined rate of change value, and wherein
restarting the gas turbine engine using the first set of lightoff
parameters further comprises turning off a starter if a third
condition is met, the third condition including: the first set of
operational parameters not being maintained for a first
predetermined amount of time; and the rotational velocity value
being greater than a third predetermined velocity value for the
first predetermined amount of time, the third predetermined
rotational velocity value greater than the second predetermined
rotational velocity value.
7. The method in accordance with claim 6 further comprising:
determining a second set of operational parameters, the second set
of operational parameters representative of a partial lightoff of
the gas turbine engine; iteratively, determining a second set of
lightoff parameters including a second flow rate; adjusting at
least one of the first predetermined amount of time, the first
predetermined rotational velocity value, the second predetermined
rotational velocity value, and the third predetermined rotational
velocity value; and restarting the gas turbine engine using the
second set of lightoff parameters until the gas turbine engine
maintains the first set of operational parameters.
8. The method in accordance with claim 6 further comprising:
determining a third set of operational parameters, the third set of
operational parameters representative of a no lightoff condition of
the gas turbine engine; iteratively, determining a third set of
lightoff parameters including a third flow rate; adjusting at least
one of the first predetermined amount of time, the first
predetermined rotational velocity value, the second predetermined
rotational velocity value, and the third predetermined rotational
velocity value; and restarting the gas turbine engine using the
third set of lightoff parameters until the gas turbine engine
maintains the first set of operational parameters.
9. The method in accordance with claim 6 further comprising:
further increasing the rotational velocity if the third condition
is not met and a fourth condition is met, the fourth condition
including the first set of operational parameters being maintained
for a second predetermined amount of time after the first
predetermined amount of time; turning off the starter if a fifth
condition is met, the fifth condition representative of a
successful starting of the gas turbine engine and including the
rotational velocity being greater than a fourth predetermined
rotational velocity value, the fourth predetermined rotational
velocity value greater than the third predetermined rotational
velocity value; and de-energizing the ignitor.
10. A system for starting a gas turbine engine, the gas turbine
engine including a rotor and a combustor having an ignitor
configured to ignite a fuel in the combustor, said system
comprising: a starter in torque communication with the rotor; a
fuel flow valve in serial flow communication with the combustor and
configured to inject the fuel into the combustor; at least one
sensor coupled to the gas turbine engine; and a controller
communicatively coupled to said starter and communicatively coupled
to said at least one sensor, said controller comprising a processor
programmed to: determine an abnormal shutdown condition of the gas
turbine engine; determine a first set of lightoff parameters for
the gas turbine engine; restart the gas turbine engine using the
first set of lightoff parameters; and iteratively, determine
subsequent first sets of lightoff parameters and restart the gas
turbine engine using a respective subsequent first set of the
determined subsequent first sets of lightoff parameters until the
gas turbine engine maintains a first set of operational parameters,
the first set of operational parameters representative of a robust
lightoff of the gas turbine engine.
11. The system in accordance with claim 10, wherein said processor
is further programmed to: determine a partial lightoff of the gas
turbine engine; iteratively, determine a second set of lightoff
parameters; and restart the gas turbine engine using the second set
of lightoff parameters until the gas turbine engine maintains the
first set of operational parameters.
12. The system in accordance with claim 10, wherein said processor
is further programmed to: determine a no lightoff condition of the
gas turbine engine; iteratively, determine a third set of lightoff
parameters; and restart the gas turbine engine using the third set
of lightoff parameters until the gas turbine engine maintains the
first set of operational parameters.
13. The system in accordance with claim 10, wherein said at least
one sensor comprises a speed sensor configured to measure a
rotational velocity of the rotor, and wherein said processor is
further programmed to transmit a starter signal having a first
value to said starter to facilitate increasing, using said starter,
the rotational velocity if a first condition is met, the first
condition including the rotational velocity being at least one of:
substantially equal to a windmill speed value; and less than a
first predetermined rotational velocity value.
14. The system in accordance with claim 13, wherein said controller
is further communicatively coupled to the ignitor, wherein the
first set of lightoff parameters includes a flow rate of the fuel
through said fuel flow valve into the combustor and an operational
status of the ignitor, and wherein said processor is further
programmed to transmit a valve signal having a first value to said
fuel flow valve to facilitate injecting the fuel at a first flow
rate, and an ignitor signal having a first value to the ignitor to
facilitate energizing the ignitor, if a second condition is met,
the second condition including the rotational velocity being
greater than a second predetermined rotational velocity value.
15. The system in accordance with claim 14, wherein said at least
one sensor further comprises a plurality of sensors comprising a
temperature sensor configured to measure a temperature of a flow of
exhaust gas exiting the gas turbine engine, wherein the first set
of operational parameters includes at least one of the exhaust gas
temperature being greater than a predetermined temperature value, a
temperature rate of change value being greater than a predetermined
temperature rate of change value, and a rate of change of the
rotational velocity being greater than a predetermined rate of
change value, and wherein said processor is further programmed to
transmit the starter signal having a second value, the second value
different from the first value, to said starter to facilitate
turning off said starter if a third condition is met, the third
condition including: the first set of operational parameters not
being maintained for a first predetermined amount of time; and the
rotational velocity value being greater than a third predetermined
rotational velocity value for the first predetermined amount of
time, the third predetermined rotational velocity value greater
than the second predetermined rotational velocity value.
16. The system in accordance with claim 15, wherein said at least
one sensor further comprises a plurality of sensors comprising a
temperature sensor configured to measure a temperature of a flow of
exhaust gas exiting the gas turbine engine, and wherein the first
set of operational parameters further includes at least one of the
exhaust gas temperature being greater than a predetermined
temperature value and a temperature rate of change value being
greater than a predetermined temperature rate of change value.
17. The system in accordance with claim 15, wherein said processor
is further programmed to: determine a second set of operational
parameters, the second set of operational parameters representative
of a partial lightoff of the gas turbine engine; iteratively,
determine a second set of lightoff parameters including a second
flow rate; adjust at least one of the first predetermined amount of
time, the first predetermined rotational velocity value, the second
predetermined rotational velocity value, and the third
predetermined rotational velocity value; and restart the gas
turbine engine using the second set of lightoff parameters until
the gas turbine engine maintains the first set of operational
parameters.
18. The system in accordance with claim 15, wherein said processor
is further programmed to: determine a third set of operational
parameters, the third set of operational parameters representative
of a no lightoff condition of the gas turbine engine; iteratively,
determine a third set of lightoff parameters including a third flow
rate; adjust at least one of the first predetermined amount of
time, the first predetermined rotational velocity value, the second
predetermined rotational velocity value, and the third
predetermined rotational velocity value; and restart the gas
turbine engine using the third set of lightoff parameters until the
gas turbine engine maintains the first set of operational
parameters.
19. The system in accordance with claim 15, wherein said processor
is further programmed to: transmit the starter signal having the
first value to said starter to facilitate further increasing, using
said starter, the rotational velocity if the third condition is not
met and a fourth condition is met, the fourth condition including
the first set of operational parameters being maintained for a
second predetermined amount of time after the first predetermined
amount of time; transmit the starter signal having the second value
to said starter to facilitate turning off said starter if a fifth
condition is met, the fifth condition representative of a
successful starting of the gas turbine engine and including the
rotational velocity being greater than a fourth predetermined
rotational velocity value, the fourth predetermined rotational
velocity value greater than the third predetermined rotational
velocity value; and transmitting the ignitor signal having a second
value, the second value different from the first value, to the
ignitor to facilitate de-energizing the ignitor.
20. A non-transitory computer-readable memory having
computer-executable instructions embodied thereon, wherein when
executed by a computing device, the computer-executable
instructions cause the computing device to: determine an abnormal
shutdown condition during operation of a gas turbine engine;
determine a first set of lightoff parameters for the gas turbine
engine; restart the gas turbine engine using the first set of
lightoff parameters; and iteratively, determine subsequent first
sets of lightoff parameters and restart the gas turbine engine
using a respective subsequent first set of the determined
subsequent first sets of lightoff parameters until the gas turbine
engine maintains a first set of operational parameters, the first
set of operational parameters representative of a robust lightoff
of the gas turbine engine.
Description
BACKGROUND
[0001] The field of the invention relates generally to gas turbine
engines, and more specifically, to a method and system for starting
gas turbine engines.
[0002] At least some turbomachinery systems, including gas turbine
engines, require special operational considerations for assisted
start control under high altitude conditions. Some gas turbine
aircraft engines, for example, operated at high altitudes utilize
assisted start control schemes that do not adapt to widely varying
operational and environmental conditions experienced at high
altitudes. At least some systems and methods for starting gas
turbine engines also do not take into account certain relevant
operational parameters, and so take additional time to effect high
altitude assisted starts given limited information available for
use by the controller.
[0003] Further, at least some known systems and methods for
starting gas turbine engines place restrictive limits upon air
start envelopes, thereby limiting the ability of some aircraft
engines to operate in high altitude airspace and at high elevation
airports. Moreover, some known controllers for starting gas turbine
engines are designed for specific engine configurations and
operational conditions, and require redesign or reprogramming upon
periodic engine upgrades including retrofit maintenance.
BRIEF DESCRIPTION
[0004] In one aspect, a method of starting a gas turbine engine is
provided. The method includes determining an abnormal shutdown
condition during operation of the gas turbine engine and
determining a first set of lightoff parameters for the gas turbine
engine. The method also includes restarting the gas turbine engine
using the first set of lightoff parameters. The method further
includes iteratively determining subsequent first sets of lightoff
parameters and restarting the gas turbine engine using a respective
subsequent first set of the determined subsequent first sets of
lightoff parameters until the gas turbine maintains a first set of
operational parameters, where the first set of operational
parameters is representative of a robust lightoff of the gas
turbine engine.
[0005] In another aspect, a system for starting a gas turbine
engine is provided. The gas turbine engine includes a rotor and a
combustor having an ignitor configured to ignite a fuel in the
combustor. The system includes a starter in torque communication
with the rotor, and a fuel flow valve in serial flow communication
with the combustor and configured to inject the fuel into the
combustor. The system also includes a plurality of sensors coupled
to the gas turbine engine, and a controller communicatively coupled
to the starter and communicatively coupled to the plurality of
sensors. The controller includes a processor programmed to
determine an abnormal shutdown condition during operation of the
gas turbine engine and determine a first set of lightoff parameters
for the gas turbine engine. The processor is also programmed to
restart the gas turbine engine using the first set of lightoff
parameters. The processor is further programmed to iteratively
determine subsequent first sets of lightoff parameters and restart
the gas turbine engine using a respective subsequent first set of
the determined subsequent first sets of lightoff parameters until
the gas turbine engine maintains a first set of operational
parameters, where the first set of operational parameters are
representative of a robust lightoff of the gas turbine engine.
[0006] In yet another aspect, a non-transitory computer-readable
memory having computer-executable instructions embodied thereon is
provided. When executed by a computing device, the
computer-executable instructions cause the computing device to
determine an abnormal shutdown condition during operation of a gas
turbine engine and determine a first set of lightoff parameters for
the gas turbine engine. When executed by a computing device, the
computer-executable instructions also cause the computing device to
restart the gas turbine engine using the first set of lightoff
parameters. When executed by a computing device, the
computer-executable instructions further cause the computing device
to iteratively determine subsequent first sets of lightoff
parameters and restart the gas turbine engine using a respective
subsequent first set of the determined subsequent first sets of
lightoff parameters until the gas turbine engine maintains a first
set of operational parameters, the first set of operational
parameters representative of a robust lightoff of the gas turbine
engine.
DRAWINGS
[0007] These and other features, aspects, and advantages of the
present disclosure will become better understood when the following
detailed description is read with reference to the accompanying
drawings in which like characters represent like parts throughout
the drawings, wherein:
[0008] FIG. 1 is a schematic illustration of an exemplary gas
turbine engine in accordance with an example embodiment of the
present disclosure.
[0009] FIG. 2 is a schematic illustration of an exemplary system
for starting a gas turbine engine that may be used with the gas
turbine engine shown in FIG. 1.
[0010] FIG. 3 is a block diagram illustrating a control system that
may be used with the system for starting a gas turbine engine shown
in FIG. 2.
[0011] FIG. 4 is a state diagram of a control logic process for the
control system shown in FIG. 3.
[0012] FIG. 5 is a flow chart of an exemplary method of starting a
gas turbine engine that may be used with the gas turbine engine
shown in FIG. 1 using the systems shown in FIGS. 2 and 3.
[0013] Unless otherwise indicated, the drawings provided herein are
meant to illustrate features of embodiments of this disclosure.
These features are believed to be applicable in a wide variety of
systems comprising one or more embodiments of this disclosure. As
such, the drawings are not meant to include all conventional
features known by those of ordinary skill in the art to be required
for the practice of the embodiments disclosed herein.
DETAILED DESCRIPTION
[0014] In the following specification and the claims, reference
will be made to a number of terms, which shall be defined to have
the following meanings.
[0015] The singular forms "a", "an", and "the" include plural
references unless the context clearly dictates otherwise.
[0016] "Optional" or "optionally" means that the subsequently
described event or circumstance may or may not occur, and that the
description includes instances where the event occurs and instances
where it does not.
[0017] Approximating language, as used herein throughout the
specification and claims, may be applied to modify any quantitative
representation that could permissibly vary without resulting in a
change in the basic function to which it is related. Accordingly, a
value modified by a term or terms, such as "about",
"approximately", and "substantially", are not to be limited to the
precise value specified. In at least some instances, the
approximating language may correspond to the precision of an
instrument for measuring the value. Here and throughout the
specification and claims, range limitations may be combined and/or
interchanged, and such ranges are identified and include all the
sub-ranges contained therein unless context or language indicates
otherwise.
[0018] As used herein, the terms "processor" and "computer" and
related terms, e.g., "processing device", "computing device", and
"controller" are not limited to just those integrated circuits
referred to in the art as a computer, but broadly refers to a
microcontroller, a microcomputer, a programmable logic controller
(PLC), an application specific integrated circuit (ASIC), and other
programmable circuits, and these terms are used interchangeably
herein. In the embodiments described herein, memory may include,
but is not limited to, a computer-readable medium, such as a random
access memory (RAM), and a computer-readable non-volatile medium,
such as flash memory. Alternatively, a floppy disk, a compact
disc-read only memory (CD-ROM), a magneto-optical disk (MOD),
and/or a digital versatile disc (DVD) may also be used. Also, in
the embodiments described herein, additional input channels may be,
but are not limited to, computer peripherals associated with an
operator interface such as a mouse and a keyboard. Alternatively,
other computer peripherals may also be used that may include, for
example, but not be limited to, a scanner. Furthermore, in the
exemplary embodiment, additional output channels may include, but
not be limited to, an operator interface monitor.
[0019] Further, as used herein, the terms "software" and "firmware"
are interchangeable, and include any computer program storage in
memory for execution by personal computers, workstations, clients,
and servers.
[0020] As used herein, the terms "non-transitory computer-readable
media" and "non-transitory computer-readable memory" are intended
to be representative of any tangible computer-based device
implemented in any method or technology for short-term and
long-term storage of information, such as, computer-readable
instructions, data structures, program modules and sub-modules, or
other data in any device. Therefore, the methods described herein
may be encoded as executable instructions embodied in a tangible,
non-transitory, computer readable medium, including, without
limitation, a storage device and a memory device. Such
instructions, when executed by a processor, cause the processor to
perform at least a portion of the methods described herein.
Moreover, as used herein, the term "non-transitory
computer-readable media" includes all tangible, computer-readable
media, including, without limitation, non-transitory computer
storage devices, including, without limitation, volatile and
nonvolatile media, and removable and non-removable media such as a
firmware, physical and virtual storage, CD-ROMs, DVDs, and any
other digital source such as a network or the Internet, as well as
yet to be developed digital means, with the sole exception being a
transitory, propagating signal.
[0021] Furthermore, as used herein, the term "real-time" refers to
at least one of the time of occurrence of the associated events,
the time of measurement and collection of predetermined data, the
time to process the data, and the time of a system response to the
events and the environment. In the embodiments described herein,
these activities and events occur substantially
instantaneously.
[0022] The systems and methods described herein provide for
starting gas turbine engines including, without limitation, under
high altitude operating conditions. The systems and methods
described herein also facilitate adaptive assisted start control
schemes to provide faster and more reliable gas turbine assistive
starting relative to known systems and methods. The systems and
methods described herein further facilitate fast and reliable
assistive starting of gas turbine engines under widely varying
operational and environment conditions such as high altitude
airspace and at high elevation airports. Furthermore, the systems
and methods described herein facilitate utilization of additional
relevant parameters to provide assistive start controllers more
information for use in improved control schemes relative to known
systems. The systems and methods described herein also loosen
operational restrictions with respect to air start envelopes for
aircraft gas turbine engines. Moreover, the systems and methods
described herein are implementable in a wide variety of gas turbine
engines for aircraft and other turbomachinery systems, and are
readily adaptable to retrofit and upgrade maintenance operations
without requiring substantial redesign. The gas turbine engine
starting systems and methods described herein are not limited to
any single type of gas turbine engine or turbomachinery system, or
operational or environment conditions thereof, but rather may be
implemented with any system requiring a robust and adaptable
assistive start control scheme to improve operational reliability,
lessen the time required for assistive start under a wide variety
of operational and environmental conditions, and increase the
number of turbomachinery systems and gas turbine engines capable of
benefiting therefrom.
[0023] FIG. 1 is a schematic cross-sectional view of a gas turbine
engine 100 in accordance with an exemplary embodiment of the
present disclosure. In the exemplary embodiment, gas turbine engine
100 is embodied in a high-bypass turbofan jet engine. As shown in
FIG. 1, gas turbine engine 100 defines an axial direction A
(extending parallel to a longitudinal axis 102 provided for
reference) and a radial direction R. In general, gas turbine engine
100 includes a fan section 104 and a core engine 106 disposed
downstream from fan section 104.
[0024] In the exemplary embodiment, core engine 106 includes an
approximately tubular outer casing 108 that defines an annular
inlet 110. Outer casing 108 encases, in serial flow relationship, a
compressor section 112 and a turbine section 114. Compressor
section 112 includes, in serial flow relationship, a low pressure
(LP) compressor, or booster, 116, a high pressure (HP) compressor
118, and a combustor 120. Turbine section 114 includes, in serial
flow relationship, an HP turbine 122, an LP turbine 124, and an
exhaust nozzle 126. Gas turbine engine 100 also includes at least
one rotating member (e.g., a rotor) that rotates at a rotational
velocity during operation of gas turbine engine 100. In the
exemplary embodiment, rotor is embodied in an HP shaft, or spool,
128 that drivingly connects HP turbine 122 to HP compressor 118.
Also, in the exemplary embodiment, an LP shaft, or spool, 130
drivingly connects LP turbine 124 to LP compressor 116. Compressor
section 112, combustor 120, turbine section 114, and exhaust nozzle
126 together define a core air flowpath 132.
[0025] In the exemplary embodiment, fan section 104 includes a
variable pitch fan 134 having a plurality of fan blades 136 coupled
to a disk 138 in a spaced apart relationship. Fan blades 136 extend
radially outwardly from disk 138. Each fan blade 136 is rotatable
relative to disk 138 about a pitch axis P by virtue of fan blades
136 being operatively coupled to a suitable pitch change mechanism
(PCM) 140 configured to vary the pitch of fan blades 136. In other
embodiments, PCM 140 is configured to collectively vary the pitch
of fan blades 136 in unison. Fan blades 136, disk 138, and PCM 140
are together rotatable about longitudinal axis 102 by LP shaft 130
across a power gear box 142. Power gear box 142 includes a
plurality of gears (not shown) for adjusting the rotational speed
of variable pitch fan 134 relative to LP shaft 130 to a more
efficient rotational fan speed.
[0026] Disk 138 is covered by a rotatable front hub 144 that is
aerodynamically contoured to promote airflow through fan blades
136. Additionally, fan section 104 includes an annular fan casing,
or outer nacelle, 146 that circumferentially surrounds variable
pitch fan 134 and/or at least a portion of core engine 106. In the
exemplary embodiment, annular fan casing 146 is configured to be
supported relative to core engine 106 by a plurality of
circumferentially-spaced outlet guide vanes 148. Additionally, a
downstream section 150 of annular fan casing 146 may extend over an
outer portion of core engine 106 so as to define a bypass airflow
passage 152 therebetween.
[0027] During operation of gas turbine engine 100, a volume of air
154 enters gas turbine engine 100 through an associated inlet 156
of annular fan casing 146 and/or fan section 104. As volume of air
154 passes across fan blades 136, a first portion 158 of volume of
air 154 is directed or routed into bypass airflow passage 152 and a
second portion 160 of volume of air 154 is directed or routed into
core air flowpath 132, or more specifically into LP compressor 116.
A ratio between first portion 158 and second portion 160 is
commonly referred to as a bypass ratio. The pressure of second
portion 160 is then increased as it is routed through HP compressor
118 and into combustor 120, where it is mixed with a fuel and
burned to provide combustion gases 162.
[0028] Combustion gases 162 are routed through HP turbine 122 where
a portion of thermal and/or kinetic energy from combustion gases
162 is extracted via sequential stages of HP turbine stator vanes
164 that are coupled to outer casing 108 and a plurality of HP
turbine rotor blades 166 that are coupled to HP shaft 128, thus
causing HP shaft 128 to rotate, which then drives a rotation of HP
compressor 118. Combustion gases 162 are then routed through LP
turbine 124 where a second portion of thermal and kinetic energy is
extracted from combustion gases 162 via sequential stages of a
plurality of LP turbine stator vanes 168 that are coupled to outer
casing 108, and a plurality of LP turbine rotor blades 170 that are
coupled to LP shaft 130 and which drive a rotation of LP shaft 130
and LP compressor 116 and/or rotation of variable pitch fan
134.
[0029] Combustion gases 162 are subsequently routed through exhaust
nozzle 126 of core engine 106 to provide propulsive thrust.
Simultaneously, the pressure of first portion 158 is substantially
increased as first portion 158 is routed through bypass airflow
passage 152 before it is exhausted from a fan nozzle exhaust
section 172 of gas turbine engine 100, also providing propulsive
thrust. HP turbine 122, LP turbine 124, and exhaust nozzle 126 at
least partially define a hot gas path 174 for routing combustion
gases 162 through core engine 106.
[0030] Gas turbine engine 100 is depicted in FIG. 1 by way of
example only. In other exemplary embodiments, gas turbine engine
100 may have any other suitable configuration including for
example, a turboprop engine.
[0031] FIG. 2 is a schematic illustration of an exemplary system
200 for starting a gas turbine engine that may be used with gas
turbine engine 100 shown in FIG. 1, as well as other gas turbine
engines and, more generally, rotatable machines including a
rotating member. The use of the same reference symbols in different
drawings indicates similar or identical exemplary elements for
purposes of illustration. Referring to FIG. 2, core engine 106
includes a core compartment 202 between outer casing 108 and
compressor 112 and turbine 114 sections. Core compartment 202 is
also sometimes referred to as an equipment compartment. Core
compartment 202 also includes an ignitor 203 coupled to at least a
portion of an interior of combustor 120. System 200 includes a
controller 204 embodied in an engine control unit (ECU) including,
without limitation a full authority digital engine (or electronics)
controller (FADEC), positioned, in the exemplary embodiment, in a
protected location proximate fan casing 146. System 200 also
includes a fuel flow valve 206 and a fuel line 208 in serial flow
communication with combustor 120.
[0032] System 200 also includes at least one starter 210 coupled in
torque communication with rotor (e.g., at least one of HP shaft 128
and LP shaft 130). In the exemplary embodiment, rotor is embodied
in HP shaft 128, and starter 210 is coupled in torque communication
with HP shaft 128 through, for example, a gear assembly (not
shown). Also, in the exemplary embodiment, starter 210 is embodied
in at least one of an electric motor and a compressed air motor,
and includes at least one electrical switching device and at least
one compressed air valve, respectively, to facilitate selectively
applying an amount of torque to HP shaft 128 to facilitate
increasing the rotational velocity thereof.
[0033] System 200 further includes a plurality of sensors including
at least one speed sensor 212, at least one temperature sensor 214,
and at least one fuel flow sensor 215. Plurality of sensors, fuel
flow valve 206, starter 210, and ignitor 203 are communicatively
coupled to controller 204, including through communication lines
(not shown) passing through outlet guide vane 148 to core
compartment 202. In an alternative embodiment, a wireless
communication protocol is employed to accomplish data communication
between controller 204 and at least one of fuel flow valve 206,
starter 210, ignitor 203, and at least one sensor of plurality of
sensors.
[0034] In operation, controller 204 receives a plurality of sensor
signals from plurality of sensors. Speed sensor 212 measures a
rotational velocity (e.g., revolutions per minute (rpm)) of HP
shaft 128. Speed sensor 212 also transmits a speed sensor signal to
controller 204 containing information representative of rotational
velocity of HP shaft 128. Temperature sensor 214 measures a
temperature of a flow of exhaust gas 216 vented from combustor 120
and diverted by exhaust nozzle 126 to an exterior 218 of gas
turbine engine 100 axially aft from core compartment 202.
Temperature sensor 214, including, without limitation, a
thermocouple device, also transmits a temperature sensor signal to
controller 204 containing information representative of temperature
of exhaust gas 216. Fuel flow sensor 215 measures a flow rate of
fuel from a fuel tank (not shown) through fuel flow valve 206 and
into combustor 120. Fuel flow sensor 215 also transmits a flow
sensor signal to controller 204 containing information
representative of flow rate of fuel.
[0035] Controller 204 transmits a plurality of control signals to
facilitate regulating the operation of ignitor 203, fuel flow valve
206, and starter 210. Controller 204 transmits a starter signal to
starter 210 to facilitate selectively applying torque to HP shaft
128 to regulate rotational velocity thereof. Controller 204 also
transmits an ignitor signal to ignitor 203 to facilitate
alternately energizing and de-energizing ignitor 203. Controller
204 further transmits a valve signal to fuel flow valve 206 to
facilitate regulating flow rate of fuel through fuel flow valve 206
into combustor 120.
[0036] FIG. 3 is a block diagram illustrating a control system 300
that may be used with system 200 shown in FIG. 2. In the exemplary
embodiment, controller 204 includes a processor 301 communicatively
coupled to a memory 302. Controller 204 is further communicatively
coupled to a monitoring station 304. In the exemplary embodiment,
where gas turbine engine 100 is embodied in an aircraft engine,
monitoring station 304 includes an aircraft cockpit including a
human machine interface (HMI) 306 including, without limitation, a
display. Through monitoring station 304, a pilot 308 receives
report signals 310 from controller 204 about operational
characteristics of control system 300. Through monitoring station
304, pilot 308 also transmits command signals 312 to controller 204
to effect changes in operational characteristics of control system
300. In an alternative embodiment, not shown, monitoring station
304 is embodied in a remote command center including, without
limitation, where gas turbine engine 100 is an unmanned aerial
vehicle engine, and where report signals 310 and command signals
312 are received and transmitted, respectively, as wireless
signals.
[0037] Also, in the exemplary embodiment, controller 204 is
embodied in a computing device and memory 302 is embodied in a
non-transitory memory 302 (e.g., one or more non-transitory
computer-readable storage media) having computer-executable
instructions embodied thereon. When executed by the computing
device, the computer-executable instructions cause the computing
device to facilitate starting gas turbine engine 100, as shown and
described below with reference to FIGS. 4 and 5.
[0038] In operation, controller 204 receives a plurality of sensor
signals 314 from plurality of sensors 316. Speed sensor 212
transmits a speed sensor signal 318 to controller 204 containing
information representative of rotational velocity of HP shaft 128.
Temperature sensor 214 transmits a temperature sensor signal 320 to
controller 204 containing information representative of temperature
of exhaust gas 216. Fuel flow sensor 215 transmits a flow sensor
signal 322 to controller 204 containing information representative
of flow rate of fuel.
[0039] Controller 204 also transmits a plurality of sensor control
signals 324 to each sensor 316 of plurality of sensors 316.
Controller 204 transmits a speed sensor control signal 326 to speed
sensor 212, transmits a temperature sensor control signal 328 to
temperature sensor 214, and transmits a fuel flow sensor control
signal 330 to fuel flow sensor 215 to regulate an operation of a
respective sensor 316 of plurality of sensors 316. For example, and
without limitation, sensor control signals 324 facilitate
regulating operation of plurality of sensors 316 including, without
limitation, their powered on status, a timing of their
measurements, and their measurement modes.
[0040] Controller 204 further transmits a plurality of control
signals to facilitate regulating the operation of ignitor 203, fuel
flow valve 206, and starter 210. Controller 204 transmits a starter
signal 332 to starter 210 to facilitate selectively applying torque
to HP shaft 128 to regulate rotational velocity thereof. Controller
204 transmits starter signal 332 having a first value to starter
210 to energize (e.g., turn on) starter 210 to facilitate applying
torque to and increasing rotational velocity of HP shaft 128.
Controller 204 transmits starter signal 332 having a second value
different from first value to starter 210 to facilitate turning off
starter 210 such that starter 210 no longer applies torque to HP
shaft 128. Controller 204 also transmits an ignitor signal 334 to
ignitor 203 to facilitate alternately energizing and de-energizing
ignitor 203. Controller 204 transmits ignitor signal 334 having a
first value to ignitor 203 to energize ignitor 203 to facilitate
combustion of fuel in combustor 120. Controller 204 transmits
ignitor signal 334 having a second value different from first value
to ignitor 203 when, for example, combustion of fuel in combustor
120 is capable of being maintained without energizing ignitor 203
during operation of gas turbine engine 100.
[0041] Controller 204 further transmits a valve signal 336 to
facilitate opening fuel flow valve 206 to further facilitate
regulating flow rate of fuel through fuel flow valve 206 into
combustor 120. Controller 204 transmits valve signal 336 having a
first value to fuel flow valve 206 to facilitate opening fuel flow
valve 206 and injecting fuel at a predetermined flow rate into
combustor 120. Also, in the exemplary embodiment, controller 204
transmits valve signal 336 having a range of values including,
without limitation, first value corresponding to a first flow rate
and a second value corresponding to a second flow rate that is at
least one of different from and substantially equal to first fuel
flow rate. Controller 204 transmitting a range of values of valve
signal 336 thus facilitates a variable flow rate of fuel through
fuel flow valve 206 into combustor 120 to further facilitate
regulating rotational velocity of HP shaft 128. Controller 204
further transmits valve signal 336 having a shutdown value
different from the first and second values to facilitate closing
fuel flow valve 206 when, for example, gas turbine engine 100 is
shutdown and injection of fuel into combustor 120 is no longer
desired.
[0042] Controller 204 also receives a plurality of status signals
337 from ignitor 203, fuel flow valve 206, and starter 210. Starter
210 transmits a starter status signal 338 to controller 204
containing information representative of an operational status of
starter 210 including, without limitation, a turned on status
versus a turned off status of starter 210. Ignitor 203 transmits an
ignitor status signal 340 to controller 204 containing information
representative of an operational status of ignitor 203 including,
without limitation, an energized status versus a de-energized
status of ignitor 203. Fuel flow valve 206 transmits a valve status
signal 342 to controller 204 containing information representative
of an operational status of fuel flow valve 206 including, without
limitation, an open status versus closed status of fuel flow valve
206, and an extent to which fuel flow valve 206 is open. In an
alternative embodiment, fuel flow valve 206 includes fuel flow
sensor 215, and valve status signal 342 includes information
contained in flow sensor signal 322. Controller 204 uses plurality
of status signals 337 to determine, for example and without
limitation, operational statuses of ignitor 203, fuel flow valve
206, and starter 210, and whether one of more of ignitor 203, fuel
flow valve 206, and starter 210 are available for use in control
system 300 to carry out the methods described herein.
[0043] Processor 301 facilitates a timing of transmitting starter
signal 332, ignitor signal 334, and valve signal 336, as well as
the values thereof, based on receipt of information by processor
301 from plurality of sensors 316. As shown and described below
with reference to FIGS. 4 and 5, processor 301 further facilitates
implementation of control system 300 in system 200 to start gas
turbine engine 100 in applications including, without limitation,
aircraft engines, land and water vehicles, and non-vehicle
turbomachinery applications.
[0044] FIG. 4 is a state diagram of a control logic process 400 for
control system 300 shown in FIG. 3. Process 400 includes a start
state 402 including, without limitation, a present operating
condition of gas turbine engine 100. In the exemplary embodiment,
present operating condition includes a high-altitude operation of
gas turbine engine 100, such as during a cruising altitude of an
aircraft. Also, in the exemplary embodiment, start state 402
includes pilot commanded assisted start of gas turbine engine 100
in an aircraft following an abnormal shutdown condition of gas
turbine engine 100. One having ordinary skill in the art will
recognize and appreciate that the systems and methods described
herein are applicable to gas turbine engines in a number of
applications other than aircraft operating at high altitude, and
where improved starting procedures as described herein are
desirable. Also, in the exemplary embodiment, processor 301
performs steps of, and transitions between steps and states of
process 400 in real-time.
[0045] Process 400 enters start state 402 upon processor 301
determining an abnormal shutdown condition during operation of the
gas turbine engine 100 requiring restarting. In the exemplary
embodiment, abnormal shutdown condition of gas turbine 100 occurs,
for example, and without limitation, after a flame-out event of gas
turbine engine 100 during high altitude cruising operation of an
aircraft. Determining abnormal shutdown condition during operation
of gas turbine engine 100 includes receiving inputs from plurality
of sensors 316 by controller 204 and processor 301. For example,
and without limitation, speed sensor signal 318 received by
controller 204 and having a value less than a first predetermined
rotational velocity value is determinative of abnormal shutdown
condition of gas turbine engine 100. Similarly, temperature sensor
signal 320 received by controller 204 and indicative of an exhaust
gas 216 temperature value substantially equal to a temperature of
exterior 218 of gas turbine engine 100 (e.g., an ambient
temperature) is determinative of abnormal shutdown condition of gas
turbine engine 100.
[0046] From start state 402, processor 301 is programmed to proceed
to a step 408. During step 408, processor 301 is programmed to
determine a first set of lightoff parameters for gas turbine engine
100. As used herein, the term "lightoff" refers to a requisite
operational event for a successful starting of gas turbine engine
100. Lightoff is substantially the opposite of flame-out, and
includes consistent combustion of fuel in combustor 120, including,
without limitation, with assistance from ignitor 203. An extent of
lightoff in gas turbine engine 100 varies over at least three
lightoff categories. First, a robust lightoff is characterized by a
full and sustained lightoff of gas turbine engine 100 that leads to
successful starting thereof after increasing rotational velocity of
rotor and de-energizing ignitor 203. Second, a partial lightoff is
characterized by partial and intermittent combustion of fuel in
combustor 120, and a diminished ability to successfully start gas
turbine engine 100 after increasing rotational velocity of rotor
and de-energizing ignitor 203. Finally, a no lightoff condition is
characterized by lack of combustion of fuel in combustor 120, and
thus a lack of ability to successfully start gas turbine engine 100
despite increasing rotational velocity of rotor using starter 210.
In the exemplary embodiment, processor 301 determines category
(e.g., extent) of lightoff of gas turbine engine 100 by using, for
example, and without limitation, information received from
plurality of sensors 316.
[0047] Lightoff parameters include at least one of predetermined
values and predetermined ranges of values for fuel flow rate
through fuel flow valve 206 into combustor 120. Lightoff parameters
also include energized status versus de-energized status (e.g., an
operational status versus a non-operational status) of ignitor 203.
As processor 301 progresses through steps of process 400 as
described herein, processor 301 uses information received through
controller 204 from plurality of sensors 316 to determine an effect
of varying lightoff parameters on gas turbine engine 100
operational parameters representative of extent of lightoff. In the
exemplary embodiment, first set of lightoff parameters are stored
in memory 302 and are predetermined based on, for example, at least
one of a type, a model, an operating mode, and a serial number of
gas turbine engine 100. Further stored in memory 302 are subsequent
sets of lightoff parameters (e.g., a second and a third set, and
subsequent sets of lightoff parameters) used, as needed, by
processor 301 to facilitate gas turbine engine 100 achieving robust
lightoff and successful starting, as further described below.
[0048] During step 408, processor 301 is further programmed to
determine a rotational velocity value of rotor (e.g., also referred
to as "N2" and core speed). Also, in the exemplary embodiment,
values of N2 represent at least one of specific values of rotor
rotational velocities at specific times and percentage values
relative to a maximum operating N2 value attainable by rotor during
operation of gas turbine engine 100. To determine rotational
velocity value, processor 301 uses information received by speed
sensor 212. Processor 301 is also programmed to determine a
rotational velocity rate of change (dN2/dt) value using a plurality
of rotational velocity values determined during step 408.
[0049] Also, during step 408, processor 301 is programmed to
compare rotational velocity value to at least one of a first
predetermined rotational velocity value and a first predetermined
range of rotational velocity values. In the exemplary embodiment,
at least one of first predetermined rotational velocity value and
first predetermined range of rotational velocity values is stored
in memory 302 and are predetermined based on, for example, at least
one of type, model, operating mode, and serial number of gas
turbine engine 100. For example, and without limitation, first
predetermined range of rotational velocity values (e.g., "R.sub.1")
is about 10% to 25% of maximum operating N2 value. Processor 301 is
also programmed to compare a first dN2/dt value to a predetermined
range of first dN2/dt values representative of a stabilization of
rotor at a windmill speed. In the exemplary embodiment, first
dN2/dt value being substantially equal to zero is further
representative of stabilization of rotor at windmill speed. Also,
during step 408, processor 301 is programmed to determine whether
or not a first condition is met. First condition includes
rotational velocity value determined during step 408 being one of
substantially equal to a windmill speed value and less than first
predetermined rotational velocity value. In an alternative
embodiment, first condition includes rotational velocity value
determined during step 408 being at least one of substantially
equal to windmill speed value and less than first predetermined
rotational velocity value. In yet another embodiment, first
condition also includes first dN2/dt value determined during step
408 being at least one of less than a predetermined first dN2/dt
value and within a predetermined range of first dN2/dt values.
[0050] If processor 301 determines that first condition is met
during step 408, processor 301 is programmed to proceed from step
408 to a step 410. During step 410, processor 301 is programmed to
determine operational status of starter 210 using information
contained in starter status signal 338 received from starter 210.
If starter status signal 338 indicates that starter 210 is not
turned on, processor 301 begins restarting gas turbine engine 100
by transmitting starter signal 332 having first value from
controller 204 to starter 210 to turn on starter 210 and apply
torque to rotor to facilitate increasing rotational velocity
thereof. From step 410, processor 301 proceeds to a step 412.
Processor 301 also proceeds from step 408 directly to step 412 if,
during step 408, processor 301 determines that first condition is
not met.
[0051] During step 412, processor 301 is programmed to use
information received by speed sensor 212 to again determine
rotational velocity value of rotor. Processor 301 is also
programmed to determine a second dN2/dt value using a plurality of
rotational velocity values determined during step 412. Also, during
step 412, processor 301 is programmed to compare rotational
velocity value to at least one of a second predetermined rotational
velocity value and a second predetermined range of rotational
velocity values. In the exemplary embodiment, at least one of
second predetermined rotational velocity value and second
predetermined range of rotational velocity values is stored in
memory 302 and are predetermined based on, for example, at least
one of type, model, operating mode, and serial number of gas
turbine engine 100. For example, and without limitation, second
predetermined range of rotational velocity values (e.g., "R.sub.2")
is about 25% to 40% of maximum operating N2 value.
[0052] Also, during step 412, processor 301 is programmed to
determine whether or not a second condition is met. Second
condition includes rotational velocity value determined during step
412 being greater than second predetermined rotational velocity
value. In an alternative embodiment, second condition includes
second dN2/dt value determined during step 412 being at least one
of greater than a predetermined second dN2/dt value and within a
predetermined range of second dN2/dt values. If processor 301
determines that second condition is met during step 412, processor
301 is programmed to proceed from step 412 to a step 414. During
step 414, processor 301 is programmed to determine operational
statuses of fuel flow valve 206 and ignitor 203 using information
contained in valve status signal 342 and ignitor status signal 340,
respectively. If valve status signal 342 and ignitor status signal
340 indicate that fuel flow valve 206 is not open and ignitor 203
is de-energized, respectively, processor 301 is also programmed to
continue restarting gas turbine engine 100. During step 414,
processor 301 continues restarting gas turbine engine 100 using
first set of lightoff parameters by transmitting valve signal 336
and ignitor signal 334 from controller 204 to fuel flow valve 206
and ignitor 203, respectively. Also, during step 414, valve signal
336 and ignitor signal 334 have values which facilitate
implementing first set of lightoff parameters in process 400 and
further facilitate gas turbine engine 100 achieving robust
lightoff. Specifically, valve signal 336 transmitted to fuel flow
valve 206 has first value to facilitate injecting fuel at a first
flow rate into combustor 120, and ignitor signal 334 transmitted to
ignitor 203 has first value to facilitate energizing ignitor 203
and igniting fuel in combustor 120. From step 414, processor 301
proceeds to a step 416. On the other hand, if processor 301
determines that second condition is not met during step 412,
processor 301 proceeds from step 412 to an end state 413, whereby
process 400 re-enters start state 402 so long as pilot has not
aborted or paused process 400.
[0053] During step 416, processor 301 is programmed to use
information received by speed sensor 212 to again determine
rotational velocity value of rotor. Processor 301 is also
programmed to determine a third dN2/dt value using a plurality of
rotational velocity values determined during step 416. Also, during
step 416, processor 301 is programmed to compare rotational
velocity to at least one of a third predetermined rotational
velocity value and a third predetermined range of rotational
velocity values. In the exemplary embodiment, at least one of third
predetermined rotational velocity value and third predetermined
range of rotational velocity values is stored in memory 302 and are
predetermined based on, for example, at least one of type, model,
operating mode, and serial number of gas turbine engine 100. In an
alternative embodiment, memory 302 stores a probabilistic model to
facilitate determining third predetermined rotational velocity
value and third predetermined range of rotational velocity values
based on at least one of type, model, operating mode, and serial
number of gas turbine engine 100. For example, and without
limitation, third predetermined range of rotational velocity values
(e.g., "R.sub.3") is about 30% to 40% of maximum operating N2
value. In the exemplary embodiment, third predetermined rotational
velocity value is greater than first predetermined rotational
velocity value and second predetermined rotational velocity value,
and R.sub.3 includes an upper range value that is greater than
upper range value of R.sub.1 and upper range value of R.sub.2.
[0054] During step 416, processor 301 is further programmed to use
information received by temperature sensor 214 to determine a
temperature value of exhaust gas 216. Processor 301 is also
programmed to determine an exhaust gas 216 temperature rate of
change value using a plurality of exhaust gas 216 temperature
values determined during step 416. Also, during step 416, processor
301 is programmed to compare exhaust gas 216 temperature value to
at least one of a predetermined exhaust gas 216 temperature value
and a predetermined range of exhaust gas 216 temperature values. In
the exemplary embodiment, at least one of predetermined exhaust gas
216 temperature value and predetermined range of exhaust gas 216
temperature values is stored in memory 302 and are predetermined
based on, for example, at least one of type, model, operating mode,
and serial number of gas turbine engine 100. In an alternative
embodiment, memory 302 stores a probabilistic model to facilitate
determining predetermined exhaust gas 216 temperature value and
predetermined range of exhaust gas 216 temperature values based on
at least one of type, model, operating mode, and serial number of
gas turbine engine 100.
[0055] Also during step 416, processor 301 is programmed to
determine whether or not a third condition is met. Third condition
includes a first set of operational parameters for gas turbine
engine 100 not being maintained for a first predetermined amount of
time. A value of first predetermined amount of time is stored in
memory 302 and is predetermined based on, for example, at least one
of type, model, operating mode, and serial number of gas turbine
engine 100. In the exemplary embodiment, first predetermined amount
of time is substantially equal to one minute. In an alternative
embodiment, first predetermined amount of time is less than one
minute. In still other embodiments, first predetermined amount of
time is greater than one minute.
[0056] Also, in the exemplary embodiment, first set of operational
parameters includes exhaust gas temperature determined during step
416 being greater than a predetermined temperature value. First set
of operational parameters also includes an exhaust gas temperature
rate of change value determined during step 416 being greater than
a predetermined temperature rate of change value. First set of
operational parameters further includes a rate of change of the
rotational velocity (e.g., third dN2/dt value) determined during
step 416 being greater than a predetermined third dN2/dt value
first set of operational parameters includes third dN2/dt value
determined during step 416 being at least one of greater than a
predetermined third dN2/dt value and within a predetermined range
of third dN2/dt values. In an alternative embodiment, first set of
operational parameters includes rotational velocity determined
during step 416 being greater than third predetermined rotational
velocity value. Thus, first set of operational parameters being
maintained for first predetermined amount of time is representative
of a presence of robust lightoff in gas turbine engine 100.
[0057] If processor 301 determines that third condition is met
during step 416, and thus robust lightoff has not occurred in gas
turbine engine 100, processor 301 is programmed to proceed from
step 416 to a step 418. During step 418, processor 301 is
programmed to determine operational status of starter 210 using
information contained in starter status signal 338 received from
starter 210. If starter status signal 338 indicates that starter
210 is turned on, processor 301 transmits starter signal 332 having
second value from controller 204 to starter 210 to turn off starter
210 such that starter 210 no longer applies torque to rotor of gas
turbine engine 100. From step 418, processor 301 proceeds to a step
420. Processor 301 also proceeds from step 416 directly to step 420
if, during step 416, processor 301 determines that third condition
is not met, and thus robust lightoff has occurred in gas turbine
engine 100.
[0058] During step 420, processor 301 is programmed to use
information received by at least one of speed sensor 212 and
temperature sensor 214 to confirm, including, without limitation,
after a second predetermined amount of time after first
predetermined amount of time has elapsed, whether or not first set
of operational parameters are still being maintained by gas turbine
engine 100. A value of second predetermined amount of time is
stored in memory 302 and is predetermined based on, for example, at
least one of type, model, operating mode, and serial number of gas
turbine engine 100. In the exemplary embodiment, second
predetermined amount of time is substantially equal to one minute.
In an alternative embodiment, second predetermined amount of time
is less than one minute. In still other embodiments, second
predetermined amount of time is greater than one minute. During
step 420, processor 301 is therefore programmed to determine
whether or not a fourth condition is met. Fourth condition includes
first set of operational parameters, and thus robust lightoff,
continuing to be maintained by gas turbine engine 100 for second
predetermined amount of time.
[0059] If processor 301 determines that fourth condition is met
during step 420, processor 301 is programmed to proceed from step
420 to a step 422. During step 422, processor 301 is programmed to
determine operational status of starter 210 using information
contained in starter status signal 338 received from starter 210.
If starter status signal 338 indicates to processor 301 that
starter 210 is turned off, processor 301 transmits starter signal
332 having first value from controller 204 to starter 210 to turn
on starter 210 and apply torque to rotor to facilitate further
increasing rotational velocity thereof. From step 422, processor
301 proceeds to a step 424. During step 424, processor 301 is
programmed to use information received by speed sensor 212 to again
determine rotational velocity value of rotor. Processor 301 is also
programmed to determine a fourth dN2/dt value using a plurality of
rotational velocity values determined during step 424. Also, during
step 424, processor 301 is programmed to compare rotational
velocity to at least one of a fourth predetermined rotational
velocity value and a fourth predetermined range of rotational
velocity values. In the exemplary embodiment, at least one of
fourth predetermined rotational velocity value and fourth
predetermined range of rotational velocity values is stored in
memory 302 and are predetermined based on, for example, at least
one of type, model, operating mode, and serial number of gas
turbine engine 100. In an alternative embodiment, memory 302 stores
a probabilistic model to facilitate determining fourth
predetermined rotational velocity value and fourth predetermined
range of rotational velocity values based on at least one of type,
model, operating mode, and serial number of gas turbine engine 100.
For example, and without limitation, fourth predetermined range of
rotational velocity values (e.g., "R.sub.4") is about 60% to 70% of
maximum operating N2 value. In the exemplary embodiment, fourth
predetermined rotational velocity value is greater than third
predetermined rotational velocity value, and R.sub.4 includes an
upper range value that is greater than upper value of R.sub.3.
Further, in the exemplary embodiment, fourth predetermined
rotational velocity value and fourth predetermined range of
rotational velocity values are representative of an idle operating
state and a successful starting of gas turbine engine 100.
[0060] Also, during step 424, processor 301 is programmed to
determine whether or not a fifth condition is met. Fifth condition
is representative of successful starting of gas turbine engine 100
and includes rotational velocity determined during step 424 being
at least one of greater than fourth predetermined rotational
velocity value and within fourth predetermined range of rotational
velocity values. If processor 301 determines that fifth condition
is met during step 424, processor 301 is programmed to proceed from
step 424 to a step 426. During step 426, processor 301 is also
programmed to determine operational statuses of starter 210 and
ignitor 203 using information contained in starter status signal
338 and ignitor status signal 340, respectively. If starter status
signal 338 indicates that starter 210 is turned on during step 426,
processor 301 is programmed to transmit starter signal 332 having
second value from controller 204 to starter 210 to turn off starter
210. If ignitor status signal 340 indicates that ignitor 203 is
energized during step 426, processor 301 is further programmed to
transmit ignitor signal 334 having second value from controller 204
to ignitor 203 to de-energize ignitor 203. Also, during step 414,
valve signal 336 and ignitor signal 334 have values which
facilitate implementing first set of lightoff parameters in process
400 and further facilitate gas turbine engine 100 achieving robust
lightoff. From step 426, processor 301 proceeds to end state 413.
Processor 301 also proceeds from step 424 directly to end state 413
if processor 301 determines that fifth condition is not met during
step 424, and thus gas turbine engine 100 has not successfully
started.
TABLE-US-00001 TABLE 1 Required Conditions For Successfully
Starting Gas Turbine Engine in Process 400. Corresponding Exhaust
Gas Required Corresponding Temperature (EGT) System Step Condition
N2 Condition Condition Action(s) 408 First Engine Windmill- EGT
< Predeter- Turn on Condition ing at N2 < Idle mined Shutdown
Starter 210 True (T); Speed (First Pre- Temp. Abnormal determined
Rota- Shutdown tional Velocity Value (PRVV)) 412 Second N2 >
Second Not Required Open Fuel Condition PRVV Flow Valve True (T)
206 & Ener- gize Ignitor 203 416 Third First Set of If
Applicable, Keep Starter Condition Operational EGT > Predeter-
210 Turned False (F); Parameters mined Temperature On Robust
Maintained for Value (PTV) and/or Lightoff First Predeter- EGT Rate
of mined Amount Change Value of Time (PAT) (RCV) > Predeter-
(Third dN2/dt > mined Temperature Predetermined Rate of Change
Third dN2/dt Value (PTRCV) Value) 420 Fourth First Set of If
Applicable, Keep Starter Condition Operational EGT > PTV and/
210 Turned True (T); Parameters Are or EGT RCV > On Robust
Maintained for PTRCV Lightoff Second PAT Confirmed (N2 > Third
PRVV) 424 Fifth N2 > Fourth Not Required Turn Starter Condition
PRVV (Idling) 210 Off & True (T); De-Energize Successful
Ignitor 203 Starting
[0061] Table 1 above summarizes steps 408 through 426 of process
400 for an exemplary embodiment. In order for gas turbine engine to
progress through step 408 to step 422, and further to achieve
successful starting and perform step 426, Table 1 shows the
requisite conditions which must be met in process 400.
[0062] Also, in the exemplary embodiment, if, during step 424,
processor 301 determines that fifth condition is not met and gas
turbine engine 100 has not successfully started, processor 301 is
programmed to selectively proceed from end state 413 to start state
402 if processor 301 again determines that starting is required (as
described above). During such a subsequent entry (e.g., iteration)
by processor 301 into process 400, processor 301 is programmed to
iteratively determine at least one subsequent first set of lightoff
parameters and again restart gas turbine engine 100 using a
respective subsequent first set of the at least one determined
first set of lightoff parameters. If, upon completion of at least
one iteration from start state 402 to step 408 and through process
400 to end state 413 through step 424, processor 301 again enters
step 408, a plurality of subsequent first sets of lightoff
parameters are determined by processor 301. Process 400 continues
in this manner until at least one of processor 301 determines first
set of operational parameters is maintained for second
predetermined amount of time during step 420 and processor 301
determines successful starting of gas turbine engine 100 during
step 424, as described above.
[0063] If, during step 420, processor 301 determines that fourth
condition is not met, and thus robust lightoff is not maintained
for second predetermined amount of time, processor 301 proceeds
from step 420 to a step 430. During step 430, processor 301 is
programmed to determine whether or not gas turbine engine 100 has
partial lightoff. Partial lightoff is determined by processor 301
based on, for example, and without limitation, exhaust gas 216
temperature rate of change value (determined during steps 416
and/or 420) being less than, by a first predetermined quantity, at
least one of predetermined exhaust gas 216 temperature rate of
change value and predetermined range of exhaust gas 216 temperature
rate of change values. Also, during step 430, processor 301 is also
programmed to determine partial lightoff based on, for example, and
without limitation, third dN2/dt value (determined during steps 416
and/or 420) being less than, by a second predetermined quantity, at
least one of predetermined third dN2/dt value and predetermined
range of third dN2/dt values. By thus comparing at least one of
exhaust gas 216 temperature value, exhaust gas 216 temperature rate
of change value, rotational velocity value, and third dN2/dt value
(determined during steps 416 and/or 420), processor 301 is also
programmed to determine a second set of operational parameters
representative of partial lightoff.
[0064] Upon determining that gas turbine engine 100 has partial
lightoff during step 430, processor 301 proceeds from step 430 to a
step 432. During step 432, processor 301 determines a second set of
lightoff parameters for use in a subsequent iteration of restarting
gas turbine engine 100, including steps 408 to 420 of process 400.
As with restarting gas turbine engine 100 using first set of
lightoff parameters, processor 301 continues restarting gas turbine
engine 100 using second set of lightoff parameters until first set
of operational parameters are maintained for first predetermined
amount of time and second predetermined amount of time. Second set
of lightoff parameters determined by processor 301 includes a
second flow rate of fuel from fuel flow valve 206 into combustor
120. In the exemplary embodiment, second flow rate is greater than
first flow rate. In an alternative embodiment, second flow rate is
less than first flow rate. In still other embodiments, second flow
rate is substantially equal to first flow rate.
[0065] Also, during step 432, processor 301 is programmed to
adjust, by at least one of increasing and decreasing, at least one
value selected from a set of values including first predetermined
amount of time, second predetermined amount of time, first
predetermined rotational velocity value, second predetermined
rotational velocity value, and third predetermined rotational
velocity value. In an alternative embodiment, during step 432,
processor 301 is also programmed to adjust at least one of
predetermined exhaust gas 216 temperature value, predetermined
range of exhaust gas 216 temperature range values, predetermined
exhaust gas 216 temperature rate of change value, and predetermined
range of exhaust gas 216 temperature rate of change values. In
still other embodiments, during step 432, processor 301 is further
programmed to adjust at least one of first dN2/dt value, second
dN2/dt value, third dN2/dt value, predetermined range of first
dN2/dt values, predetermined range of second dN2/dt values, and
predetermined range of third dN2/dt values. Thus, during step 432,
processor 301 adjusts at least one value of the above listed
predetermined values, stores the adjusted value(s) in memory 302,
and implements a partial lightoff adaptive control scheme used for
restarting gas turbine engine 100 using second set of lightoff
parameters. For example, and without limitation, during step 432,
processor 301 increases fuel flow rate for use in step 414 to
second flow rate greater than first flow rate. Also, for example,
and without limitation, during step 432, processor 301 adjusts at
least one of first (R.sub.1), second (R.sub.2), and third (R.sub.3)
predetermined ranges of rotational velocity values. Thus, during
step 432, processor 301 implements partial lightoff adaptive
control scheme (e.g., for use in steps 408, 410, 412, 414, 416,
418, and 420) to facilitate establishing favorable physical
conditions for maintaining first operational parameters for first
predetermined amount of time and second predetermined amount of
time, and for achieving a successful start in gas turbine engine
100, as described above.
[0066] If, after processor 301 again restarts gas turbine engine
100 using second set of lightoff parameters and partial lightoff
adaptive control scheme, processor 301 again determines partial
lightoff during step 430, processor 301 again enters step 432.
During such a subsequent entry (e.g., iteration) by processor 301
to step 432, processor 301 is programmed to iteratively determine
at least one subsequent second set of lightoff parameters and again
restart gas turbine engine 100 using at least one respective
subsequent second set of lightoff parameters. During subsequent
iterations of step 432, processor 301 is programmed to make further
adjustments, as described above, including, without limitation, at
least one of value of the above listed predetermined values that
has not been adjusted by processor 301 during a prior iteration of
step 432. For example, if, during prior iteration of step 432,
processor 301 increased R.sub.2 from about 25% to 40% of maximum
operating R.sub.2 value to about 30% to 45% of maximum operating N2
value, during a subsequent step 432 iteration, processor 301 is
programmed to at least one of further increase R.sub.2, further
decrease R.sub.2, and return R.sub.2 to a range used in prior
iteration of step 432. Similarly, during subsequent iterations of
step 432, processor 301 is programmed to determine subsequent
second sets of lightoff parameters by, for example, at least one of
further increasing second flow rate, returning second flow rate to
a value substantially equal to first flow rate, and decreasing
second flow rate to a value less than first flow rate.
[0067] From step 432, processor 301 is also programmed to re-enter
step 408 and proceed to restart gas turbine engine 100 using second
set of lightoff parameters. If, however, during step 430, processor
301 determines gas turbine engine 100 has no lightoff condition,
processor 301 proceeds from step 430 to a step 434, rather than to
step 432. No lightoff condition is determined by processor 301
based on, for example, and without limitation, exhaust gas 216
temperature rate of change value (determined during steps 416
and/or 420) being less than, by a third predetermined quantity
greater than first predetermined quantity, at least one of
predetermined exhaust gas 216 temperature rate of change value and
predetermined range of exhaust gas 216 temperature rate of change
values. Also, during step 430, processor 301 is programmed to
determine no lightoff condition based on, for example, and without
limitation, third dN2/dt value (determined during steps 416 and/or
420) being less than, by a fourth predetermined quantity greater
than second predetermined quantity, at least one of predetermined
third dN2/dt value and predetermined range of third dN2/dt values.
By thus comparing at least one of exhaust gas 216 temperature
value, exhaust gas 216 temperature rate of change value, rotational
velocity value, and third dN2/dt value (determined during steps 416
and/or 420), processor 301 is also programmed to determine a third
set of operational parameters representative of no lightoff
condition.
[0068] Upon determining that gas turbine engine 100 has no lightoff
condition, processor 301 proceeds from step 430 to step 434. During
step 434, processor 301 determines a third set of lightoff
parameters for use in a subsequent iteration of restarting gas
turbine engine 100, including steps 408 to 420 of process 400. As
with restarting gas turbine engine 100 using first set of lightoff
parameters, processor 301 continues restarting gas turbine engine
100 using third set of lightoff parameters until first set of
operational parameters are maintained for first predetermined
amount of time and second predetermined amount of time. Third set
of lightoff parameters determined by processor 301 includes a third
flow rate. In the exemplary embodiment, third flow rate is greater
than first flow rate and second flow rate. In an alternative
embodiment, third flow rate is less than at least one of first flow
rate and second flow rate. In still other embodiments, third flow
rate is substantially equal to first flow rate and second flow
rate.
[0069] Also, during step 434, processor 301 is programmed to
adjust, by at least one of increasing and decreasing, at least one
value selected from the set of values including first predetermined
amount of time, second predetermined amount of time, first
predetermined rotational velocity value, second predetermined
rotational velocity value, and third predetermined rotational
velocity value. In an alternative embodiment, during step 434,
processor 301 is also programmed to adjust at least one of
predetermined exhaust gas 216 temperature value, predetermined
range of exhaust gas 216 temperature range values, predetermined
exhaust gas 216 temperature rate of change value, and predetermined
range of exhaust gas 216 temperature rate of change values. In
still other embodiments, during step 434, processor 301 is further
programmed to adjust at least one of first dN2/dt value, second
dN2/dt value, third dN2/dt value, predetermined range of first
dN2/dt values, predetermined range of second dN2/dt values, and
predetermined range of third dN2/dt values. Thus, during step 434,
processor 301 adjusts at least one value of the above listed
predetermined values, stores the adjusted value(s) in memory 302,
and implements a no lightoff condition adaptive control scheme used
for restarting gas turbine engine 100 using third set of lightoff
parameters. For example, and without limitation, during step 434,
processor 301 increases fuel flow rate for use in step 414 to third
flow rate greater than first flow rate and second flow rate. Also,
for example, and without limitation, during step 434, processor 301
adjusts at least one of first (R.sub.1), second (R.sub.2), and
third (R.sub.3) predetermined ranges of rotational velocity values.
Thus, during step 434, processor 301 implements no lightoff
condition adaptive control scheme (e.g., for use in steps 408, 410,
412, 414, 416, 418, and 420) to facilitate establishing favorable
physical conditions for maintaining first operational parameters
for first predetermined amount of time and second predetermined
amount of time, and for achieving a successful start in gas turbine
engine 100, as described above.
[0070] If, after processor 301 restarts gas turbine engine 100
using third set of lightoff parameters and no lightoff condition
control scheme, processor 301 again determines no lightoff
condition during step 430, processor 301 again enters step 434.
During such a subsequent entry (e.g., iteration) by processor 301
to step 434, processor 301 is programmed to iteratively determine
at least one subsequent third set of lightoff parameters and again
restart gas turbine engine 100 using at least one respective
subsequent third set of lightoff parameters. During subsequent
iterations of step 434, processor 301 is programmed to make further
adjustments, as described above, including, without limitation, at
least one of value of the above listed predetermined values that
has not been adjusted by processor 301 during a prior iteration of
step 434. For example, if, during a prior iteration of step 434,
processor 301 increased R.sub.2 from about 25% to 40% of maximum
operating R.sub.2 value to about 30% to 45% of maximum operating N2
value, during a subsequent step 434 iteration, processor 301 is
programmed to at least one of further increase R.sub.2, further
decrease R.sub.2, and return R.sub.2 to a range used in prior
iteration of step 434. Similarly, during subsequent iterations of
step 434, processor 301 is programmed to determine subsequent third
sets of lightoff parameters by, for example, at least one of
further increasing third flow rate, returning third flow rate to a
value substantially equal to first flow rate, and decreasing third
flow rate to a value less than first flow rate.
[0071] FIG. 5 is a flow chart of an exemplary method 500 of
starting a gas turbine engine that may be used with gas turbine
engine 100 shown in FIG. 1 using system 200 and control system 300
shown in FIGS. 2 and 3, respectively. In the exemplary embodiment,
method 500 includes determining 502 an abnormal shutdown condition
of the gas turbine engine (e.g., gas turbine engine 100). Method
500 also includes determining 504 first set of lightoff parameters
for the gas turbine engine. Method 500 further includes restarting
506 the gas turbine engine using the first set of lightoff
parameters. Method 500 also includes iteratively determining 508
subsequent first sets of lightoff parameters and restarting the gas
turbine engine using a respective subsequent first set of the
determined subsequent first sets of lightoff parameters until the
gas turbine engine maintains the first set of operational
parameters, where the first set of operational parameters is
representative of robust lightoff of the gas turbine engine.
[0072] The above-described systems and methods for starting gas
turbine engines provide for improved assistive starting including,
without limitation, under high altitude operating conditions,
relative to known systems and methods. The above-described systems
and methods also facilitate adaptive assisted start control schemes
to provide faster and more reliable gas turbine assistive starting
relative to known systems and methods. The above-described systems
and methods further facilitate fast and reliable assistive starting
of gas turbine engines under widely varying operational and
environment conditions such as high altitude airspace and at high
elevation airports. Furthermore, the above-described systems and
methods facilitate utilization of additional relevant parameters to
provide assistive start controllers more information for use in
improved control schemes relative to known systems. The
above-described systems and methods also loosen operational
restrictions with respect to air start envelopes for aircraft gas
turbine engines. Moreover, the above-described systems and methods
are implementable in a wide variety of gas turbine engines for
aircraft and other turbomachinery systems, and are readily
adaptable to retrofit and upgrade maintenance operations without
requiring substantial redesign. The above-described gas turbine
engine starting systems and methods are not limited to any single
type of gas turbine engine or turbomachinery system, or operational
or environment conditions thereof, but rather may be implemented
with any system requiring a robust and adaptable assistive start
control scheme to improve operational reliability, lessen the time
required for assistive start under a wide variety of operational
and environmental conditions, and increase the number of
turbomachinery systems and gas turbine engines capable of
benefiting therefrom.
[0073] An exemplary technical effect of the methods, systems, and
apparatus described herein includes at least one of: (a) providing
improved assistive starting of gas turbine engines including at
high altitude operating conditions; (b) facilitating adaptive
assistive start control schemes to provide faster and more reliable
gas turbine engine assistive starting; (c) facilitating fast and
reliable assistive starting of gas turbine engines under widely
varying operational and environmental conditions such as high
altitude airspace and at high elevation airports; (d) facilitating
utilization of additional relevant parameters to provide assistive
start controllers more information for use in improved control
schemes; (e) loosening operational restrictions with respect to air
start envelopes for aircraft gas turbine engines; (f) providing
implementation in a wide variety of gas turbine engines for
aircraft and other turbomachinery systems; and (g) enabling
adaptability to retrofit and upgrade maintenance operations without
requiring substantial redesign.
[0074] Exemplary embodiments of systems and methods for gas turbine
engine starting are described above in detail. The above-described
systems and methods are not limited to the specific embodiments
described herein, but rather, components of systems or steps of the
methods may be utilized independently and separately from other
components or steps described herein. For example, the methods may
also be used in combination with a plurality of gas turbine engines
requiring a coordinated assistive start control scheme, and are not
limited to practice with only a single aircraft gas turbine engine
as described herein. Rather, the exemplary embodiments may be
implemented and utilized in connection with many other
turbomachinery systems requiring a robust and adaptive assistive
start control scheme for improved operation as described
herein.
[0075] Although specific features of various embodiments may be
shown in some drawings and not in others, this is for convenience
only. In accordance with the principles of the systems and methods
described herein, any feature of a drawing may be referenced or
claimed in combination with any feature of any other drawing.
[0076] Some embodiments involve the use of one or more electronic
or computing devices. Such devices typically include a processor,
processing device, or controller, such as a general purpose central
processing unit (CPU), a graphics processing unit (GPU), a
microcontroller, a reduced instruction set computer (RISC)
processor, an application specific integrated circuit (ASIC), a
programmable logic circuit (PLC), a programmable logic unit (PLU),
a field programmable gate array (FPGA), a digital signal processing
(DSP) device, and/or any other circuit or processing device capable
of executing the functions described herein. The methods described
herein may be encoded as executable instructions embodied in a
computer readable medium, including, without limitation, a storage
device and/or a memory device. Such instructions, when executed by
a processing device, cause the processing device to perform at
least a portion of the methods described herein. The above examples
are exemplary only, and thus are not intended to limit in any way
the definition and/or meaning of the term processor and processing
device.
[0077] This written description uses examples to disclose the
embodiments, including the best mode, and also to enable any person
skilled in the art to practice the embodiments, including making
and using any devices or systems and performing any incorporated
methods. The patentable scope of the disclosure is defined by the
claims, and may include other examples that occur to those skilled
in the art. Such other examples are intended to be within the scope
of the claims if they have structural elements that do not differ
from the literal language of the claims, or if they include
equivalent structural elements with insubstantial differences from
the literal language of the claims.
* * * * *